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Thread: Talking Technical on Tech Cameras

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    Talking Technical on Tech Cameras

    The current Tech Camera users and 'soon to be' need many more detailed technical discussion concerning the use of camera, away from 'brand' based discussion. Focusing is a Tech Camera issue not ALPA's or Linhof's, Tilting properly is a Tech Camera's challenge not A-S's or Cambo's.

    So, I am starting a new thread to talk about many technical issues we are facing with Tech Camera. I will start with my experiences of challenges that I faced and the solutions that I came up for my Tech Camera.

    I hope you don't mind if I am reposting two previous posts from "Arca Rm3di" to start my story.

    Jae M

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    Re: Talking Technical on Tech Cameras

    I've had my Rm3di for as long as Jack has, since August of 2011. I had F-Metric Compact 6x9 before that and used both camera with P45 DB.

    The focusing is the main challenge with both View and Technical camera whether one is using Tilt or Swing or not. Tilt and/or Swing just makes the challenge bigger, at least by a magnitude of 10. None of currently available methods of focusing; GG, LV, tethered shoot and using a laser range finder, are a perfect solution.

    I am only going to talk about 'focusing' here, not 'composing' or 'Tilt.'

    For me at least, GG is not an option. I tried too many different types of GG and loupes with my F-Metric and gave up on the idea of using GG with MFDB. Personally, I only have a limited experiences with the LV with MFDB, and I hope that we may have the 'perfect' solution soon. A tethered shoot provides the best possible focus but by means of trials and errors.

    The reason why I picked Rm3di is based on the possibility of achieving the perfect focus every time utilizing its very precise 'helical' focus ring and precise measurement of object distances. It is my assumption that Arca-Swiss originally designed its Rm3di with the same design criteria. Arca-Swiss is finally making available 'E-module', which I am only familiar with by reading about it, to measure 'precise' distance.

    Both ALPA and Arca-Swiss are providing means of 'precise' focus; HPF rings from ALPA and a built-in Helical focus from Arca-Swiss, with different twists. There are two significant differences between two methods; rotational pitch and indexing method. Many are focusing on either advantage or dis-advantage of the larger rotational pitch of helical focus ring of Arca-Swiss over the HPF ring of ALPA.

    I will use the example of using SK35XL on both mounting methods.



    As can be seen, Arca-Swiss helical ring needs to rotate approximately 4 times as much as HPF ring. You make your own conclusion if it is good for your workflow or not.

    Another difference is the method of marking distance scale. HPF ring is marked with the actual object distance for a particular lens while A-S Helical ring is just simple index (0 to 34.4 for each revolution, up to 5 revolutions if necessary).

    Each has both pros and cons; HPF ring eliminate one step of 'look up table' that A-S uses; measure the distance with a laser range finder then dial in the distance while you have to look up a table which converts the measured distance to a focus setting for Arca-Swiss. On the other hand, HPF ring only shows 9 discrete distance marking between 2.5 m and infinity while the look up table from Arca-Swiss shows 34 discrete focus settings for the same distance range. HPF ring has tick mark for each angular degree but has the actual distance marking at every 5 degrees (except first 5 degrees from infinity). For example, it show the distance setting of 9.64 m at 5 degree and 4.86 m setting at 10 degree, therefore, you have to make a quick interpolation if your distance measurement is 7.5 m to find the correct focus setting. Done? The answer is 6.5 degree. ALPA makes it available a print out of HPF ring setting for each degree in PDF format for each lens, and they are 7 pages per lens.

    The real advantage of the simple indexing used by Arca-Swiss is when one takes advantage of an iPhone and some mathematic. It is possible to develop a 'lens equation' which converts the object distance into the required angular rotation for an individual lens, and run it on an iPhone. That's what I had in mind when I chose Rm3di and I've been using it from the beginning. Measure the distance with a laser finder, then tap in the number into an iPhone and it will show the exact focus setting; i.e., White 7.3

    The development of 'lens equation' requires the combination of 'optical lens equation' and 'curve fitting' by numerical analysis. A simple 'optical lens equation' does not work in entire object distance range since the modern lenses for MF are very complex with multiple lens elements. It is necessary to measure the actual focus settings for different distances or just use the data provided by Arca-Swiss. I did my own measurement.

    Can this method be used with HPF ring? It can be done if the distance markings are replaced with a simple angular degree indexing of 0 - 270, by pasting a simple adhesive tape over distance marking. It is not easy to find 37.5 degree from the scale marked with 9.64, 4.86,3.27, etc.

    For me, Rm3di provides the best solution to make perfectly accurate focus under the presently available technologies; Leica Disto D5 and a home brewed program on an iPhone.

    I will discuss the subject of Tilt or Swing on a separate post.


    Jae M
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    Re: Talking Technical on Tech Cameras

    I discussed the challenge of making perfectly accurate focus using tech cameras with MFDB in previous post (#31).

    A quick summary, at least in my case, the best possible method with the presently available technologies to achieve perfect focus is by using 'lens equation' with accurate object distance measurement and a precisely indexed focus ring. A lens equation, for a specific lens with a specific focusing system, can be developed mathematically. The 'lens equation' will provide the required angular rotation of a focus ring for a measured object distance.

    First, I would like to 'rant' against all View Camera and Tech Camera manufacturers for their failure to promote (i.e. to educate their customers) properly how to use the features they are building into their camera. It is a shame that they let the customers to rely upon HF (hyper focal) or 'focus stacking' for proper focusing, or '35mm rule of thumb' for lens tilt calculation after spending a small fortune on equipment that boast 'multi mega pixels', '13 f-stop dynamic range' and 'lens with resolving power to see the sub atomic particles', etc. Why can they develop and provide more than a 'satisfactory' solutions to the challenges their customers face? Enough with ranting.

    Let't talk about Tilt or Swing in Tech Camera application.



    A simple geometric diagram for Tilt (both camera and lens) is shown above.

    The Plane of Sharp Focus is defined by two points photographer select to be in 'sharp' focus, Near Subject (or Object) and Far Subject. Camera Height, Camera Tilt angle and a specific lens are also defined by photographer to compose the image properly. The lens Tilt Angle and the required Focus Distance are the results of these five input data (the location of Near and Far Subjects, Camera Height reference to the ground, a lens focal length and Camera Tilt Angle). In addition, Near and Far Wedges of Acceptable Sharpness (Angular DOF) are defined by a user selected CoC.

    The real challenge of using Tilt or Swing with View Camera or Tech Camera is not finding a lens Tilt Angle but the required Focus Distance after a tilt is made. Harold Merklinger published two books (The Ins and OUTs of Focus, Focusing the View Camera) on the subject of Lens Tilt in details.

    Once I was satisfied with the results of 'Lens Equation' in achieving a perfect focus with a measured Object Distance, I decided to tackle the challenge of Lens Tilt (or Swing). It is rather complex geometric calculations but doable using a spreadsheet, such as Excel or Numbers. It took me much longer than I expected (my mathematical brain atrophied significantly over last 40 years) but I completed the project and have been using since last Spring.


    The picture above shows the setup I use for both leveled and lens tilted application. It maintains the exact geometric configuration between Rm3di and Disto 5 so I can always accurately measure the Object Distance or Near (Far) Object locations. Since all Disto measurement are offset from Lens Axis, Lens Nodal Point and DB sensor plane, proper corrections are made in the program.

    Near (and Far) Object locations should be measured by their horizontal and vertical distance from the lens nodal point. Disto 5 has a function to measure them (Direct Horizontal Distance).

    I made a quick shot this morning after reading "Torger's" comment. I used SK90, placed two $20 bills on the floor (1.96m and 3.22m away from the camera, and the nose of Andrew Jackson was the targets), camera was tilted 23.8 degree and the camera height was 0.96m. The required lens tilt was 4.82 degree and the calculated focal distance was 2.14m, therefore the index setting of Red 22.1.


    Images are directly from C1 without any enhancement.

    100% of Front US$20 bill.

    100% of Back US$20 bill.

    One additional picture I took while working on the program, Lens Swing. I superimposed 100% images of two blocks, front and back.



    This is the one man's story to use a tech camera, Rm3di, for its full potential.

    There are several mechanical designs of Rm3di which I wish they improve soon.

    1. There are no indentations (mechanical click) for both vertical and horizontal shift center positions.
    2. Thumb dial for Lens Tilt needs major improvement, for both accuracy of setting and ease of use.
    3. Helical ring is too tight to rotate. I understand its need to stay at a set point but the friction could be much less.
    4. Focus setting point should be a 'fine line' much closer to the index markers.

    I will discuss my attempt of distributing the program commercially in next post.

    Jae Moon
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by JGR View Post
    I haven't quite got my head around Jae's math and how I would use the Disto 5 should I decide on purchasing one vs the E-Module though. I think further explanation for my aging grey matter is required (hint hint) :-)!


    In my two previous posts, I discussed methods I developed to maximize the usability of a Tech Camera, in my case Rm3di. It is very important to remember that I am talking about techniques of using a 'machine' accurately, not about creating artistic masterpieces. Some may argue that my methods of focusing is an overkill and there are ways to get 'good enough' instead of 'absolute.' Again, I am being a mechanic who 'fine tune' a Formula 1 car for a driver so he can take advantage of it and show its maximum performance on the track and may win the race (for me, as a driver, I am taking advantage of the camera to it's maximum potential but haven't won any race yet. But just puttering around with a finely tuned machine is lots of fun too).

    The main attractions of a Tech (and View) Camera to a photographer are two folds (my personal opinion); first, the best possible optical lenses available; second, mechanical 'movements' - shift, tilt, swing and accurate focus ring. The main challenges of a Tech Camera to a photographer who purchased it is its difficulty to use, mainly how to focus accurately with or without Tilt/Swing.

    CONTROL based on visual feedback is very powerful and useful. See how we steer cars, we don't measure the angle of turn we need to make before making a precise turn of steering wheel (in other hand, we usually end up in accidents if we try keep on driving with badly fogged up windshield), see how Apollo 13 crews steered the crippled module to a successful reentry based on visual feedback of seeing the earth through the module window (but they could do it only because they are NOT ordinary weekend Piper flyers).

    A Tech Camera with MFDB lacks an 'Excellent' visual feedback to focus an 'Excellent' lens via an 'Excellent' camera movement. In control theory, the weakest link determines the final result. The combined accuracy of a Tech Camera is 60% if the accuracy of the visual feedback using a GG (or my dated P45 display) is 60% even with 100% accurate lens and camera movement. The same analogies apply to the Lens component of Tech Camera (reduced lens performance by stopping down the aperture) and Focusing component (i.e., relying on HFD or Infinity focus setting).

    How do we measure distance (to focus accurately)?

    - It is not likely a Tech Camera will have an Auto Focus such as Nikon and Canon.
    - LiveView may solve the problem in 2-3 years (IQ4xx).
    - A tethered shoot has its place.
    - eModule from A-S? First of all, it is only for RM camera from A-S. I only know how it work and what it does based on what I have read from this Forum. My present impression is that it is an excellent concept but not-so excellent method of measuring distance. It measures (let me know if I am wrong) the distance the way we manually focus a SLR camera, rotate a focus ring until the image is sharp, then translate the angular rotation into focus distance. I don't know yet how many rotations it requires to focus from Infinity to let say 1 meter. With A-S Focus Ring, SK35 rotates slightly over 360 degree (1 rotation), SK47 rotates 720 degrees (2 rotations), and SK90 rotates 1,620 degrees (4.5 rotations) to focus from infinity to 1 meter. The same control theory applies here, the weakest link determines the final result. The number of rotation of eModule focus ring determines the effectiveness of Rm3di's helical focus ring. If the focus ring of eModule rotates 360 degree (Canon 5DII rotates approximately 90 degree), its accuracy with SK35 will not diminish, with SK47 it will diminish to 50%, and with SK 90 it will diminish to 25%. (I apologize in advance if eModule reads the distance by other means, not relying on the angular rotation of focus ring.)
    - I gave up on GG for my own reason and do not have opinion on it anymore.
    - Laser Rangefinder provide the most accurate means at a reasonable price and is portable. It would have been a breakthrough product if eModule was based on a laser rangefinder.

    How to use a Laser Rangefinder (LR)?

    A LR is one tool any Tech Camera users should have. With HPF ring(s) or with printed card(s) for A-S, accurate focus can be made with a one-click distance measurement. Keep the picture of the cards in iPhone, and you will always have it with you. You may get a simple App which provides HFD and Near and Far Focus distance with a measured distance or make a quick spreadsheet. Without any intention of insulting our forum members, it is very important to read manual and go through all functions. Spend an hour with it. I have met too many who have Disto but didn't know it could be in either metric or imperial mode, different decimal points, the location of sensor, front or back assignment of the reference point, etc. I have Disto manual in both iPhone and iPad in PDF format to refresh my memory how to measure the horizontal and vertical distance of a inclined object point.

    How to use LensTilt?

    SIMPLE LENS TILT
    If you are limiting the lens tilt with the 'Plane of Sharp Focus' that is parallel to horizontal ground, and not to tilt the camera, it is easy to find both lens tilt angle and the required focus distance. You can have a simple spreadsheet with only two user input; f and J, and use it in an iPhone. The equations are as follow:

    alpha = arcsin (f/J), where alpha is lens tilt angle, f is lens focal length in mm, and J is the vertical distance between lens axis and your Plane of Sharp Focus in mm.
    Fd = J / sin(alpha), where Fd is the calculated focus distance in mm.

    If you are focusing the ground plane, J is the camera height from ground; if you are focusing on items on horizontal table top, J is the vertical distance between the lens axis and table top; if you are focusing on the street below from rooftop, J is the vertical distance between lens axis and the street, etc.
    J is always located vertically along the lens nodal point.

    It should be noted that the conventional concepts of DOF or HFD do not apply once a lens tilt is made. DOF is not two parallel planes from the lens anymore but a wedge (above and below the Plane of Sharp Focus).
    HFD also lose its relevancy and I will explain it using examples:
    - SK35 at 8.0 aperture and CoC setting of 3 pp of P45 (0.02mm)
    - Ground to be the plane of Sharp Focus

    - If Camera Height is 1 meter, Tilt angle is 2.1, Focus distance is 29.6 meter and HFD is 8.1 meter
    - If Camera Height is 1.5 meter, Tilt angle is 1.4, Focus distance is 68.8 meter and HFD is 8.1 meter

    TILTED PLANE OF SHARP FOCUS
    If you want to have the Plane of Sharp Focus in angle to the ground (to have small cactus flowers in foreground and tall cactus tree in the back in focus) without camera tilt, the calculation become more complex. You have to have several more user input for tilted Plane of Sharp Focus; vertical and horizontal location of both Near and Far Object relative to the Lens Nodal Point. And J is not anymore the vertical distance between the lens axis and the ground and will be calculated based on the locations of Near and Far Object.

    TILTING CAMERA
    Tilting the camera in addition to the lens tilt makes geometry even more complex.

    What is 'Lens Equation'?

    A "lens equation' will translate the measured object distance into the distance between the lens nodal point and the sensor plane for a specific lens. In place of 'lens equation', ALPA provides HPF rings and A-S provides the helical focus ring and lookup tables and both work 'good enough'. It is an industry convention that the object distance is between the sensor plane (not the nodal point) and the object. The equation can be developed with the data provided by manufacturers (ALPA and A-S) or with your own calibration data.

    It streamlines the workflow using 'calculation' on an iPhone, more accurate without 'mental' interpolation, and provide a means to enhance the usability of HPF ring with a simple modification.

    Jae M
    Last edited by Jae_Moon; 1st April 2013 at 17:22.
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    Re: Talking Technical on Tech Cameras

    more power to you, Jae

    i would buy your app and i do place value on software, and in addition, you know the value i place on hardware

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    Re: Talking Technical on Tech Cameras

    I'm speaking as someone who has developed and sold (with limited but some success) an iOS app, I think you've underestimated the potential of the iOS sales. People are not going to put up $125 for something they do not know will work for them or not, and there is no way to test it. Don't get me wrong, I'm sure your app is great and works as advertised, but the above is unfortunately the scenario you have to live with in in the iOS world. Why not make it available for $9.99 for a few weeks and see what happens, you may be surprised and have nothing really to loose......

    Just a thought.

    Cheers, -Peter

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    Re: Talking Technical on Tech Cameras

    Might want to think canon/Nikon shooters as well as that market is very large.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Jae_Moon View Post
    One thing you didn't consider is the other important issues I described, very small target market. I am almost positive that a great majority of existing user base (500) will buy $10 app, and exhaust the market, netting me a couple thousands dollars. I didn't say it but $125 does not make a viable venture.

    Jae M
    Well - the price of $125 was actually my point - it will not work for an iOS app. I still think you completely underestimate the potential scale of the market. Many people are interested in this stuff, as pointed out by Guy - the DSLR market is huge. At $10 (or less) you can tap into this and by economy of scale you will be surprised how quickly things add up. This is my experience, I initially also thought the target market was too small, but was proven wrong.....

    Good luck with it.

    Cheers, -Peter

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    Re: Talking Technical on Tech Cameras

    Actually I would design it first for the Nikon/canon crowd at the 9.99 rate than within the marketing of it mention the 125 rate for high end technical cameras. Let the big market feed the small market. Just a thought
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com
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    Re: Talking Technical on Tech Cameras

    There is some good advice here - an app for $125 aimed at the tech camera market is a tough sell. Not because the product isn't worthy, but rather that market is more of a "can do myself" group of modest size who can be quite stingy. For example, consider Rodenstock's DOF calculator - a modest seller to this group at $30.

    OTOH, aiming for the larger market for less $ but for more sales might open up the doors: you may achieve a critical mass, where the product becomes known and shared. You might be very surprised - yes, its a different model, but its the new world. Think Canon instead of Sinar. Keep the little bits that the tech camera people need, and you might have a win-win. Again, what have you got to lose?

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Geoff View Post
    There is some good advice here - an app for $125 aimed at the tech camera market is a tough sell. Not because the product isn't worthy, but rather that market is more of a "can do myself" group of modest size who can be quite stingy. For example, consider Rodenstock's DOF calculator - a modest seller to this group at $30.

    OTOH, aiming for the larger market for less $ but for more sales might open up the doors: you may achieve a critical mass, where the product becomes known and shared. You might be very surprised - yes, its a different model, but its the new world. Think Canon instead of Sinar. Keep the little bits that the tech camera people need, and you might have a win-win. Again, what have you got to lose?
    yes, what have you got to loose? the app is already finished, or at least almost - as far i understood.

    regarding the price point: $125 is a lot of money for an iphone app.
    don't want to depreciate your work, i'm sure it's very useful and you did a good job, but for about $140 i can purchase lightroom4 which has a whole lot more functionality and a lot more hours of usage in my workflow. the percentage of tilted images per year will never reach 100% but every picture runs through lightroom...
    okay, the market is a whole lot bigger for adobe, than for your app, but considering the much bigger development investment and running the whole department of the lightroom team is also much much more cost intensive.

    and the fact that it's not possible to get trials of ios software can't be denied.

    for my workflow, the ability to use the iphone as a viewfinder is not important, i'm happy with my vario finder and it cannot run out of battery during intense use.
    considering the various needs of tech cam users may also be a point to keep the entry not too big. maybe providing upgrades to the full usability.
    www.thomasebruster.com
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    Re: Talking Technical on Tech Cameras

    The topics are going to the direction which was not my intent when I posted my experience stories. I included 'going commercial' to properly end the story, that's all.

    I appreciate it very much all your comments on 'business' aspect of the story. But as the title of this thread indicates, Let's talk Technical on Tech Camera, not business models.

    Jae M

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    Re: Talking Technical on Tech Cameras

    Workflow for Lens Tilt (with or without camera tilt) using my method.


    As shown in my previous post, I use the combination of RRS rail and clamps to mount both Rm3di and Disto on Cube (actually I have a PhotoClam) to maintain fixed locational relationship between lens nodal point and Disto laser sensor. It is not feasible to measure X, Y location of an object while handholding a Disto. Cube is a perfect tripod head for Tilt since it provide easy pan/pitch adjustment.

    1. Select a right focal length lens with selected subject.
    2. Roughly frame the image (near and far objects) using whatever method you use (I use Sony RX100 as my optical view finder). Tilt the camera if needed but no tilt of the lens yet. I usually rely on built-in P45 display with roughly estimated focusing just to see if my four edges are properly located.
    3. You now fixed the camera height and the camera tilt (if you are using it). Measure and note the camera tilt angle and the camera height.
    4. Aim at Near Object point with Disto laser point using Cube's pitch control. Measure X, Y location. Repeat the same for Far Object point.
    5. Reset the camera tilt angle that you noted before (so camera is back to the desired composition).
    6. Enter the data; camera height, camera tilt angle, camera focal length, near and far object location coordinates.
    7. You will have required Lens Tilt angle and the calculated Focus Distance (and Index Setting with Lens Equation)
    8. Take picture with proper tilt and focus setting. You will have a pin prick sharp focused image.
    9. Since you can see your image very clearly now, you may want to adjust your composition.
    10. Many minor adjustments can be done by 'shift R/L and U/D' instead by camera height or camera tilt angle. No adjustments are needed to the lens tilt or focus setting when you do 'shift'.
    11. If you decide to use different focal length lens, let say 47mm instead of 35mm to tighten the composition, only thing you have to do is to select other lens in the program. No new measurement are needed. Change the lens, adjust both tilt and focus setting and shoot. You will have another pin prick sharp image.

    From step 3 to 8, what I called 'mechanical' part, will take you 2 minutes. You are free to spread your artistic imagination wings to make a masterpiece once the 'mechanical' challenges are overcome. I usually carry my Macbook Pro with me and do tethered shoot while I fine tune the image.


    Jae M

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    Re: Talking Technical on Tech Cameras

    A low Tech but a serious challenge.

    My camera equipment is getting heavier and heavier and a mile is getting longer and becoming an uphill as I age. Since I do mainly landscape photo, the challenge is finding a way to pack the equipment safely for the flight and be as light as possible so I can hike 3-4 miles one way without a porter.

    I carry Rm3di with three SK lenses and P45. In addition, I have Gitzo Series 3/3-section, Cube, some rails, filters, shade, Disto, and a 13" Retina Macbook Pro, etc. I pack tripod and Cube in a checked-in duffel bag during the flight and carry it on my shoulder while hiking (Cube in backpack).

    So I needed a solution to pack Tech Camera and miscellaneous gears and a Macbook Pro 13 in a regular backpack. I wanted to use a regular backpack for its light weight (roughly 2# vs over 8# with camera bags) even though it does not have any serious padding to protect the gears. I decided on Jansport Outdoor series which has fully padded back and comfortable shoulder and waist straps and 3L hydration pack. A laptop can be safely carried in a backpack with a stiff plastic clipboard to protect it from bending force. Now, I needed a case with strong shell to protect the camera, 3 lenses and a DB, and small enough to fit into a regular backpack and does not add much weight. As a weekend 'classical bookbinder' I knew the answer is a case made of Davey Board (a type of paper board for book covers and cases. it is acid free and warp resistant) with stiff foam sheets cut-to-fit lenses and camera. The outer dimension of Rm3di is 8.5"x7.5"x2" and SK90 is 3" tall (SK35 and 47 are shorter) and P45 is 2.75" or so, and diameter of lenses are 3.75".

    I made a box with outer dimension of 10"x10"x6.5", with 3 layers of 1.1" foam, cut-to-fit for 3 lenses and a DB, and 2 layers of 1.1" foam, cut-to-fit for Rm3di, inside the box. I covered it with goat skin leather, for look and the added structural strength. It fit snuggly inside the main compartment of Jansport, and Macbook goes next, and miscellaneous stuffs go in additional compartments.

    The box with camera, lenses and DB weighs 9#. I put the shoulder strap that A-S provided with camera on the box, just in case I have to check in the backpack with small regional airlines so I can carry it with me along laptop, so far no need for that.

    Now I can go places where I want to shoot more easily. I may have to come up with other solution in next 10 years; as I say, it get heavier and heavier.


    Jae M















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    Re: Talking Technical on Tech Cameras

    Jae,

    Thank you for posting this valuable information.

    is this 'Lens equation' available anywhere for calculating it all when the camera is tilted. would love to play with it in excel or similar.

    Personally I have focus nailed pretty well for level camera, and tilt for most of what I do, but soon as i point the camera down at the subject, ability to focus goes out the door !. (note, I use a Cambo).

    Regards

    Mark.

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Marlyn View Post
    Jae,

    Thank you for posting this valuable information.

    is this 'Lens equation' available anywhere for calculating it all when the camera is tilted. would love to play with it in excel or similar.

    Mark.

    Please PM me so we can discuss.

    Jae M

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    Re: Talking Technical on Tech Cameras

    Jae


    this is an interesting thread - while I don't have a tilt/swing lens for our medium format gear yet, we do have a Canon 24mm T/S lens - so I have been working on understanding the principles. Threads like this have been a help - so thanks.


    Mal

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by malmac View Post
    Jae


    this is an interesting thread - while I don't have a tilt/swing lens for our medium format gear yet, we do have a Canon 24mm T/S lens - so I have been working on understanding the principles. Threads like this have been a help - so thanks.


    Mal


    Mal:

    Thank you. I do also have Canon 5D2 but no tilt lens. I was alway wondering how the high quality LiveView (such as Canon) would fit into the workflow that involves Lens Tilt or Camera Tilt. Have you tried to visually focus using the LiveView for the simple lens tilt (no camera tilt and focusing on horizontal plane, i.e. the ground)?

    I have P45 (no LV) and have been reading that the LV of IQ1 series are not 'there' yet. I am wondering if the high quality LV with CMOS in MFDBs would function as well as the 'bright' GG of the bygone era of 8x10 or 4x5 in overall workflow. I tend to believe that the usability of an on-camera display is not only depending on its resolution but also the size of screen. Maybe the high quality LV on an iPad like device is the solution.


    Jae M

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    Re: Talking Technical on Tech Cameras

    Jae

    I hope , my question belongs into this thread .
    Looking at the LINHOF TECHNO and the ALPA as example . ( can't say anything about ARCA , CAMBO , SILVESTRI , SINAR and others )

    The TILT/SWING axis for the TECHNO goes right through the center of the lens .
    This is IMO a big advantage for focusing .
    With the ALPA , the TILT/SWING axis is either at the bottom or the side of the lens mount to the camera . That makes focusing more difficult .

    How do these technical differences influence your Scheimpflug calculations , if at all ?
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Jae_Moon View Post
    Mal:

    Thank you. I do also have Canon 5D2 but no tilt lens. I was alway wondering how the high quality LiveView (such as Canon) would fit into the workflow that involves Lens Tilt or Camera Tilt. Have you tried to visually focus using the LiveView for the simple lens tilt (no camera tilt and focusing on horizontal plane, i.e. the ground)?

    I have P45 (no LV) and have been reading that the LV of IQ1 series are not 'there' yet. I am wondering if the high quality LV with CMOS in MFDBs would function as well as the 'bright' GG of the bygone era of 8x10 or 4x5 in overall workflow. I tend to believe that the usability of an on-camera display is not only depending on its resolution but also the size of screen. Maybe the high quality LV on an iPad like device is the solution.


    Jae M


    Jae, this image was taken with 5D2 with 24mm T/S lens at about f7.1 with the camera tilted and a few degrees of lens tilt.

    I used live view to get the focus at a balanced sharpness - though I did compromise a little because the camera was only about 12 inches from the back of the bike - so perspective was quite extreme. In the original image you can read all the lettering on the instrument panel including the milage. So the lens did a pretty good job from where I sit.

    I never use the LV on the IQ180 back - I use the focus mask and do the shoot, check focus mask then zoom in to test for focus accuracy. Apart from the time spent to zoom and check the screen is absolutely reliable in telling me if I have nailed the focus or missed by even a small amount.


    Mal
    Last edited by malmac; 4th April 2013 at 13:01. Reason: spelling error
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post
    Jae

    The TILT/SWING axis for the TECHNO goes right through the center of the lens .
    This is IMO a big advantage for focusing .
    With the ALPA , the TILT/SWING axis is either at the bottom or the side of the lens mount to the camera . That makes focusing more difficult .

    How do these technical differences influence your Scheimpflug calculations , if at all ?


    Jürgen:

    I can tell only for three Tech Cameras; ALPA, A-S RM series and Cambo. All three camera systems have the axis of lens tilt/swing through the center of the lens. I think you are mistaken (I am 99% sure) about the ALPA. As you can see from the attached photo, the axis is in the middle.


    It is true that it is easier to focus with the axis in the middle of lens when you are doing by visually, either with GG or LV. My old A-S F-Metric Compact had the option called Orbix which put the tilt axis in the middle.

    With the camera where the tilt axis is not located along the lens axis, you have to make an adjustment for the distance between the lens nodal point and DB sensor plane by a small a mount (= tan (alpha) x L, where alpha is lens tilt angle and L is the distance between tilt hinge and the lens center) in calculating the focus distance).


    Hope it answers your question.

    Jae M
    Last edited by Jae_Moon; 4th April 2013 at 13:39.

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by malmac View Post

    Jae, this image was taken with 5D2 with 24mm T/S lens at about f7.1 with the camera tilted and a few degrees of lens tilt.

    I used live view to get the focus at a balanced sharpness - though I did compromise a little because the camera was only about 12 inches from the back of the bike - so perspective was quite extreme. In the original image you can read all the lettering on the instrument panel including the milage. So the lens did a pretty good job from where I sit.

    I never use the LV on the IQ180 back - I use the focus mask and do the shoot, check focus mask then zoom in to test for focus accuracy. Apart from the time spent to zoom and check the screen is absolutely reliable in telling me if I have nailed the focus or missed by even a small amount.

    Mal

    Mal:

    A great shot, you proved that one can make great Tilt shots with a good LV display.

    As I indicated in my earlier posts, my P45 do not have the LV and I don't have T/S lens to try with my 5D2.

    So, the question is, why everyone who have IQ series DBs not use the LV of IQ display for the Tilt, or for focusing instead of focus mask? My premise was maybe the size of the display is as much important as the pixel density in usability of the built-in display.

    Jae M

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Jae_Moon View Post
    Jürgen:

    I can tell only for three Tech Cameras; ALPA, A-S RM series and Cambo. All three camera systems have the axis of lens tilt/swing through the center of the lens. I think you are mistaken (I am 99% sure) about the ALPA. As you can see from the attached photo, the axis is in the middle.


    It is true that it is easier to focus with the axis in the middle of lens when you are doing by visually, either with GG or LV. My old A-S F-Metric Compact had the option called Orbix which put the tilt axis in the middle.

    With the camera where the tilt axis is not located along the lens axis, you have to make an adjustment for the distance between the lens nodal point and DB sensor plane by a small a mount (= tan (alpha) x L, where alpha is lens tilt angle and L is the distance between tilt hinge and the lens center) in calculating the focus distance).


    Hope it answers your question.

    Jae M
    I am asking this , because with my ARCA F-LINE Metric , I have an ORBIX
    function , which makes focusing easy . You mentioned that as well .

    Your image shows the old style of TILT/SWING adapter .
    The new one is , as far as I can see , different .
    ALPA OF SWITZERLAND - Hersteller herausragender Kameras - ALPA tilt/swing adapter 0° - 5°, 34 mm
    Have a look to the different images of the adapter .
    I am glad you see my point and that your APP calculation will take care of this .

    I will give the ALPA people a call to get the correct answer .
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

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    Re: Talking Technical on Tech Cameras

    Considering the money most of us spend on all of this stuff, i'd pay $125 in a heartbeat.

    Guy does have a good point though. As usual!

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post

    Your image shows the old style of TILT/SWING adapter .
    The new one is , as far as I can see , different .
    ALPA OF SWITZERLAND - Hersteller herausragender Kameras - ALPA tilt/swing adapter 0° - 5°, 34 mm
    Have a look to the different images of the adapter .
    I am glad you see my point and that your APP calculation will take care of this .

    I will give the ALPA people a call to get the correct answer .
    Jürgen:

    Yes, it sure look like the hinge of tilt/swing is at the end. With this type, if we are correct with our assumptions, you have to make the adjustment for proper focus distance.

    Jae M
    Last edited by Jae_Moon; 5th April 2013 at 06:52.

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    Re: Talking Technical on Tech Cameras

    I got an answer from ALPA .

    For the T/S adapters 17mm and 34 mm , the hinge point is in the center of the adapter and therefore in the center of the lens .
    The shown images on the ALPA pages do not show the hinge point . Hidden .

    The same is valid for the old style T/S adapters , but here the hinge point can be seen .
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post
    I got an answer from ALPA .

    For the T/S adapters 17mm and 34 mm , the hinge point is in the center of the adapter and therefore in the center of the lens .
    The shown images on the ALPA pages do not show the hinge point . Hidden .

    The same is valid for the old style T/S adapters , but here the hinge point can be seen .
    Jürgen:

    Thank you for the clarification. I will correct my previous post.

    Jae M
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    Re: Talking Technical on Tech Cameras

    I have just ordered 2 adapters , one T/S17 and one MULTI USE 17 .
    I still need my HR DIGARON 4,5/40mm get adapted for SB17 and then
    . . . . . I can tilt like mad with my 40 and 90 mm DIGARONS .
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

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    Re: Talking Technical on Tech Cameras

    The challenges of using Tilt do not stop at finding a proper lens tilt angle and the required focus distance. The conventional concept of DOFs, two parallel planes perpendicular to lens axis, does not hold once a lens tilt is made, Instead we have 'Wedges of Near and Far Focus' which are tilted up (for Near Wedge) and tilted down (for Far Wedge) from the Plane of Sharp Focus.

    In the example shown, I defined the surface of water as Near Object and the middle of building as Far Object, and resulting Plane of Sharp Focus tilted up from the reference plane (water surface). Please note the 'line diagram' is 'exaggerated view' to show the concept.

    While composing the image, I like to know how far up and down from the 'far object' would be in focus, or will the steeple in focus, or will the surface below the dam be in focus, etc. The advantage of using the 'mathematics' is all those information are readily available for any specific settings for lens tilt.

    Lens was tilted 1.5 degree and the Plane of Sharp Focus was 8 degree tilted up from the reference. A quick check indicated that the Near Wedge at the distance of Far Object was 5.7 meter above the reference plane while the Far Wedge was at 1.8 meter below the reference plane (ensuring that both water level below the dam and the top of tree are within the wedges). Then, I checked the wedges boundary at the distance where the steeple is located, and the results show that the Near Wedge at the distance was 12.5 meter above the reference plane while the Far Wedge was at 2.8 meter below the reference plane (ensuring that the steeple is within the wedges).

    Too much math instead of image making? It is not, at least in my case since I have a tool, and the whole 'math' process took me less than 5 minutes, and it allowed me to have more 'image making' time.

    Jae M


    Last edited by Jae_Moon; 9th April 2013 at 18:26.

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    Re: Talking Technical on Tech Cameras

    at which aperture did you get this wedge?
    and at which distance did you focus?
    www.thomasebruster.com
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by photomgraphy View Post
    at which aperture did you get this wedge?
    and at which distance did you focus?
    Aperture was 8.0, the camera was 1 meter above the reference level (water) and I picked the near object at the ref. level and 4 meter (approximate) away and the far object at 2.1 meter above the ref. and 21 meter away.

    By tilting lens, I could put entire objects; from the water just below the tripod to the top of steeple, within the wedges of Sharp Focus.

    Disto does not work well on reflective surface so I picked a nearby branch sticking out and made an estimate from it.

    Jae M
    Last edited by Jae_Moon; 9th April 2013 at 12:29.

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    Re: Talking Technical on Tech Cameras

    Jae

    You can Not set the distance to two different values .
    Did you focus to the average of 21m + 4m = 12,5m ? ? ?
    Regards . Jürgen .
    -----------------------------------------------------------------------------------

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post
    Jae

    You can Not set the distance to two different values .
    Did you focus to the average of 21m + 4m = 12,5m ? ? ?
    Jürgen:

    Sorry, the calculated focus distance was 10.5 meter. Another benefit is I could take the 'screen grap' of iPhone for records..

    Jae M

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post
    Jae

    You can Not set the distance to two different values .
    Did you focus to the average of 21m + 4m = 12,5m ? ? ?
    To clarify, just in case. Near and Far Objects defines the Plane of Sharp Focus, lens tilt angle and the Wedges of Sharp Focus, but the tilted lens will aim at a point somewhere between those two points that is located on the PSF. The calculated focus distance is the distance between that point and the DB image plane.


    Jae M
    Last edited by Jae_Moon; 9th April 2013 at 18:23.

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    Re: Talking Technical on Tech Cameras

    This thread has fried my brain... And I've got a full day ahead of me! Will have to come back and read properly after work.
    In all seriousness, I've been in need of a hard core technical explanation of tilt / swing for some time. I use a Linhof Techno and use the GG the set tilt angles referencing the iPhone app Tilt Calculator, but often end up scratching my head wondering what the hell I'm doing and why!

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by jotloob View Post
    For the T/S adapters 17mm and 34 mm , the hinge point is in the center of the adapter and therefore in the center of the lens...
    For shorter focal length lenses any displacement when tilting is probably very small using such a system. However, as the lens gets progressively further away from the axis of tilt, focus shift is unavoidable. For instance:


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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by f8orbust View Post
    For shorter focal length lenses any displacement when tilting is probably very small using such a system. However, as the lens gets progressively further away from the axis of tilt, focus shift is unavoidable. For instance:


    I think Jürgen had a discussion with ALPA and was told that all ALPA tilt adapters have the tilt hinge along the lens axis. I think the hinge is hidden but still located along the lens axis for the picture you attached.

    In these cases, there are NO Lens shift due from the lens tilt. If the tilt hinge is located at the bottom, a simple adjustment is made to compensate the added distance between the lens nodal point and the DB image sensor (see previous post).


    Jae Moon

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by tjv View Post
    This thread has fried my brain... And I've got a full day ahead of me! Will have to come back and read properly after work.
    In all seriousness, I've been in need of a hard core technical explanation of tilt / swing for some time. I use a Linhof Techno and use the GG the set tilt angles referencing the iPhone app Tilt Calculator, but often end up scratching my head wondering what the hell I'm doing and why!


    I agree it is not a simple subject.

    I cannot remember the link now, but I saw a photo of a very large camera setup that a German (?) company built which had computer controlled and electro-mechanically actuated system for all camera movements; tilt, swing, focus, etc.

    Short of having that kind of gears, I think there are three approaches one can take with Lens Tilt (my personal opinion) with present technology:

    1. Do a simple rule of thumb (or at least develop a simple look-up table)
    This option should be limited to the lens tilt only (no camera tilt) and to the objects that are on the horizontal level; ground or tabletop, street below, etc.
    The mathematical formulae for this method is rather simple to use with the spreadsheet. They are listed on the previous post (#4). You will have very accurate tilt angle and the focus distance setting that you do not need a visual confirmation.

    2. Do with Visual Confirmation using GG, tethered or built-in Display.
    The mathematical formulae are rather complex if you want either to tilt the camera or to focus on a tilted plane or to do combined, and you should rely on visual feedback. The challenge in this case is that you have two variables; tilt angle and focus distance (you have to guess the tilt angle first then focus, then repeat until both are correct). There are many articles available online how to tilt and to focus using visual feedback.

    3. Do with mathematical formulae. This is my approach and it has been working for me. I am considering a way to make the formulae available to others, and evaluating if there are 'real needs' by users.


    Jae Moon


    ps

    4. Be an 'Outlier' as in Malcolm Gladwell's book 'Outliers'. Gladwell told stories of 10,000 hours of practice required to be Bill Gates, Midori, star hockey players, and Wall Street Super Lawyers, etc. Develop your own way by repeated practices until you are happy with the methods and the results.
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Jae_Moon View Post
    In these cases, there are NO Lens shift due from the lens tilt...
    Assume all camera adjustments are neutral. If we tilt the lens about it's centre, the distance between it and the sensor remains the same on cameras such as the A/S ML-2, Techno etc. (all cameras that have an 'orbix' style tilt). On pancake cameras like Alpa and RM3D/i, long lenses in particular are 'hung out' on long lensboards, with the axis of tilt displaced (obvious in my previous picture). So, when you tilt the lens, the distance between its centre and the film plane changes - it gets less.
    Last edited by f8orbust; 12th April 2013 at 21:00. Reason: confusing diagram removed !

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by f8orbust View Post
    Assume all camera adjustments are neutral. If we tilt the lens about it's centre, the distance between it and the sensor remains the same on cameras such as the A/S ML-2, Techno etc. (all cameras that have an 'orbix' style tilt). On pancake cameras like Alpa and RM3D/i, long lenses in particular are 'hung out' on long lensboards, with the axis of tilt displaced (obvious in my previous picture). So, when you tilt the lens, the distance between its centre and the film plane changes - it gets less.

    See attachment: b = b1 + b2 and f < b1 + b2 so f < b. Also, you can see that because e and g are different, a non-orbix style tilt will change the shape of the subject compared to an orbix style tilt (where a = c, even when the lens is tilted).

    N.B. This is a simplified diagram assuming a simple symmetrical lens design where it's 'centre' is simply defined - obviously with retrofocus lens designs the 'centre' can be displaced quite significantly from where we imagine it might be.

    I think you are half right and I am half wrong (or the other way around )

    It is a little difficult to explain by writing but I will try.

    1. All three Tech Cameras have the lens tilt hinge along the lens axis (but not at the lens nodal point). I agree Orbix (also Cambo T/S lenses) would have the hinge closer to the nodal point.
    2. Your depiction for 'Orbix Style Tilt' is not correct. The light path does not refract and it should look like to your 'Tilt about a displaced axis'.
    3. 'Focus Shift' occurs with ALPA and A-S RM due to the horizontal distance between the DB sensor plane and the Tilt hinge location.The length of lens focal lens does not have any effects.


    With a set focus setting, the focus distance (=Xf) is the distance between the lens nodal point and the DB sensor plane along the lens axis. And Xf can be expressed as the sum of two distances; distance from lens nodal point to lens tilt hinge and the distance from lens tilt hinge to DB sensor plane. The first distance, between lens nodal point and the lens tilt hinge along the lens axis does not change whether the lens is tilted or not, but the second distance, between the lens tilt hinge and the DB sensor plane along the lens axis changes when the the lens is tilted. This change (Focus Shift) is the function of the lens tilt angle and the second distance (between the lens tilt hinge and the DB sensor plane), not the function of lens focal length.

    At a given lens tilt angle, the error will be proportionally larger as the distance between the lens tilt hinge and the DB plane increases (which is fixed for AS RM camera at approximately 12 mm and is much larger for ALPA with its thicker adapter plates in addition to camera body depth).

    For example, AS RM can tilts up to 5 degree and would results in the focus error of 0.046 mm or 0.6 in helical focus ring setting. At more common tilt with wide angle lens, 2 degree, the error is 0.007 mm or 0.1 in helical focus ring setting.

    I can only speculate for ALPA that the error would be a bit larger since the distance between the lens tilt hinge and the DB sensor plane is much larger than 12 mm.

    However, it should be noted that this 'Focus Shift' is only relevant to the application where the Tilt Angle and the Focus Distance is mathematically calculated. Both ALPA and AS RM cameras will function just like any view cameras with Orbix like feature to focus using the Visual Confirmation since the lens tilt hinge is located along the lens axis.

    I hope this makes sense.

    Jae Moon

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    Re: Talking Technical on Tech Cameras

    Jae, that all makes sense - not sure what happened with my thinking - got caught in at least two minds + general brain fade I suspect.

    Just a couple of points. 1) I wasn't trying to depict refraction - now that would be a step too far for my brain - simply the distance from the 'centre' of the lens to the edges of the sensor. 2) As long as the 'centre' of the lens is in front of the axis of rotation, then focal length isn't related to focus-shift, since the distance from the axis of tilt to the sensor plane is the same for whatever lens is stuck on the T/S adapter, and however much it is tilted. However this is only true of lenses in front of the axis of tilt, once the 'centre' of a lens is behind it (such as with some retrofocus lenses or lenses on recessed boards) then the value of 'actual distance' (and thus the degree of 'focus shift') will vary according to focal length. 3) Longer focal length lenses tend to require more tilt on certain occasions (e.g. landscape: foreground to background in focus) which means the 'actual distance' in your diagram tends to be greater with longer focal length lenses and thus the effect is greater, both of 'focus shift' and the appearance of the subject on the sensor, due to the divergence of the values e and f on my amended diagram.

    Jim

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    Re: Talking Technical on Tech Cameras

    It is not a simple task to do Tilt/Swing correctly but it is not a Brain Surgery either. Two previous posts by me and f8orbust should not scare anyone, they are only theoretical discussions between two 'gear heads'.

    The 'focus shift' that we discussed does not affect when you do the focusing by visual confirmation; GG, built-in display or tethered (and it does not exists in a real world situation since you do not know the 'calculated focus distance'). It applies only if you calculate the required focus distance. But even if you do use the calculation, the fix is just adding an equation to correct, therefore, there is no focus shift in any Tech Camera with any focal length using mathematical formulae.

    It is true that a longer lens requires bigger tilt than a short lens under the same settings (thus increasing the focus shift in calculation), but it is also true that a longer lens is much more forgiving to the focus shift since the longer lens has longer focus adjustment range. For example, the focal length changes 0.15 mm for SK90 and 0.02 mm for SK35 when you move the object distance from 2.3 m to 2.4 m.

    The conclusion? Don't let these theoretical talks scare you, find a way that suits you and keep working on it until you are happy with your results.

    It is a simple 'Cost/Benefit' optimization; to obtain the best results (to your eyes) with the minimum efforts (in your part) to achieve it.


    Jae M

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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by Jae_Moon View Post
    alpha = arcsin (f/J), where alpha is lens tilt angle, f is lens focal length in mm, and J is the vertical distance between lens axis and your Plane of Sharp Focus in mm.
    Fd = J / sin(alpha), where Fd is the calculated focus distance in mm.

    Jae M
    Quote Originally Posted by Jae_Moon View Post

    - SK35 at 8.0 aperture and CoC setting of 3 pp of P45 (0.02mm)
    - Ground to be the plane of Sharp Focus

    - If Camera Height is 1 meter, Tilt angle is 2.1, Focus distance is 29.6 meter and HFD is 8.1 meter
    - If Camera Height is 1.5 meter, Tilt angle is 1.4, Focus distance is 68.8 meter and HFD is 8.1 meter

    Jae M
    jae, i'm a little confused about the formulars:

    if i try to calculate the above settings the result is:

    arcsin(35/1000)= 0,035
    these are radiens right? if i want degrees - i'll have to multiply with 180/pi

    and
    1000/sin(2,1)= 1158,5 there i should have inserted in the radians not degrees
    am i right?

    how about the formular of HFD and DOF?

    thanks for the interesting discussion
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    Re: Talking Technical on Tech Cameras

    Tilt = arcsin (35/1000) = arcsin (0.035) = 2.01 degrees
    Focus Distance = 1000 / sin (2.01) = 28.5m

    All distances in mm (unless otherwise stated) and angles in degrees.
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    Re: Talking Technical on Tech Cameras

    ok, but when i insert the formular in excel =arcsin(0,035) the result is 0,03500175????
    obviously that's not correct ...
    what does this program do?
    when i multiply with (180/3,14) i get: 2

    what did i wrong?
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    Re: Talking Technical on Tech Cameras

    although i don't understand why excel calculates in radiant - it does.
    so i have to convert to degree.
    formular: =GRAD(ARCSIN(F/J)) --- german version: grad=degree ;-)
    Last edited by photomgraphy; 14th April 2013 at 03:44.
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    Re: Talking Technical on Tech Cameras

    Quote Originally Posted by photomgraphy View Post
    jae, i'm a little confused about the formulars:

    if i try to calculate the above settings the result is:

    arcsin(35/1000)= 0,035
    these are radiens right? if i want degrees - i'll have to multiply with 180/pi

    and
    1000/sin(2,1)= 1158,5 there i should have inserted in the radians not degrees
    am i right?

    how about the formular of HFD and DOF?

    thanks for the interesting discussion

    Without getting into a Math tutoring :

    There are different units in math and physics; Deg C or Deg F, meter or yard, etc. In most higher level math, the unit of measuring angular degree is 'radian' not 'degree'.
    A circle is 360 degree or 2 x Pi radian, where Pi is 3.1415.....
    In order to use Excel or Numbers, you have to convert your 'degree' into 'radian' by RADIAN (# of degree) and convert 'radian' into 'degree' by DEGREE (# of radian).

    Harold Merklinger published two books (The Ins and OUTs of Focus, Focusing the View Camera) and you can download PDF version from online site. Just google 'Harold Merklinger' and you will see it. You will learn all about DOF, HFD, Tilt, etc.


    Jae Moon

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    Re: Talking Technical on Tech Cameras

    thanks got it, now lets see if my english is good enough to understand it ;-)
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    Re: Talking Technical on Tech Cameras

    Tech Camera and Digital Back


    Since my purchase of P45 in the spring of 2006 Phase One have introduced three upgrades; P+ series, IQ1xx and IQ2xx. I have faced the temptations to upgrade to newer model with each upgrade and went thru my own 'justification/rationalization' processes.

    First of all, I am not a professional, doing OK financially and have a reasonably understanding wife. Therefore, the decision to upgrade or not is wholly depends on my ability of convincing myself if an upgrade is justified.

    I used P45 with H2 and AS F-Metric for five years until I replace both with AS RM camera in 2011. P45 worked well with H2 since H2 had an excellent auto-focus and a great optical viewfinder (I was using the display of P45 mainly for checking histogram). I also wanted to use my F-Metric with P45 since I had four great Schneider lenses (35, 47, 90, 210) but it didn't worked out for me (difficulty of focusing with GG).

    It was an easy decision not to upgrade to P+ series since I had 'Skip One Generation' policy and I believed 39 MPx were more than enough with my 24" printer (so no need to look at P65+).

    With IQ1xx, it took a longer debate internally since it had a strong selling point, a 'better display.' 'Better focusing and composing' with the new display would mean that I could use my F-Metric more with better results. About the same time period, I started to notice Tech Camera (ALPA in the beginning) as a possible replacement to my F-Metric since I liked the idea of focusing with accurate object distance measurement. But it still lacked a 'view finder' the new IQ1xx provides. Then, I read the review of AS RM camera in Luminous Landscape (both reviewers didn't care much) and noticed the feature called 'Indexed Focusing,' which turn a light-bulb in my head on. After that, my evaluation was focused on two approaches of accurate focusing; with 'focus mask' in an IQ1xx versus 'indexed focus' with laser rangefinder. In the end, I decided to go with AS Rm3di and to skip another generation of upgrade.

    Now, I am facing with another temptation, IQ2xx. It is reasonably easy for me to assume that the Image processing technologies have improved significantly during past seven years, and I can justify to upgrade with that assumption alone. The key selling point of IQ2xx, a direct wi-fi connection to an iOS device, is a nice feature but I am not sure the premium is worth 2.1 pounds saving in weight from Macbook Pro 13 Retina (or 1.5 pound from Macbook Air 13) against carrying an iPad.

    So now I am tossing between getting an used IQ160 (hoping many would sell their 160s to get 260s) and skipping another generation.

    Jae Moon

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    Re: Talking Technical on Tech Cameras

    This is one of the most useful threads I have read in a long time.

    But the math required is beyond an old geezer like me. Long time since I went to school and even then I flunked math.

    So publish and sell an aplication my friend, I'll be the first in line. Now, if only I could find my glasses.
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